gas discharge tube indentification

Sep 11, 2007 2 Replies
J

I have some GDTs that I can't find any info on. Here are the markings:


3P90L4 - 3 leaded ceramic CM3-90 - 3 leaded ceramic CPC9119M - 3 leaded ceramic

I would like to use them for surge protection on the cable where it enters the house. I plan on mounting them in a small metal box with f-connectors at each end. The cable is grounded to a ground rod, I don't know how long and was installed by the cable company with 3ft of 12ga wire to ground.



If these can't be identified, how can I test them for breakdown voltage?



Thanks Jay


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F

On Tue, 11 Sep 2007 19:30:48 -0400, Jay1028 put finger to keyboard and composed:

I'm guessing they are 90V types. The "91" may mean 9 x 10^1.

Anyway I found the following table in this document:

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Table of Tolerances of popular Gas Discharge Arresters

Uag/N +25%/-20% min Uag max ----------------------------- 230V 184V 288V 90V 72V 113V

Uag/N +/-20% min Uag max ----------------------------- 90V 72V 108V 230V 184V 276V

I don't know the specs for cable applications, but FWIW the above document has this to say about telephony:

"The most popular gas discharge arrester is used in telephony and has a nominal static sparkover voltage Uag/N of 230V with tolerance range of +25%/-20%. The Uag measured should lie in the range from 184V to

288V."

- Franc Zabkar

Please remove one 'i' from my address when replying by email.
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J

The standard way to see the characteristics of a device is to put it on a curve tracer.

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